The invention relates to a rescue-unit comprising an automatically inflatable floating element which is kept folded in a housing containing a bottle of compressed gas having a valve actuated by depressing it and a valve-actuating mechanism comprising a preloading device and support-elements blocking the actuation of the valve, the support-elements, upon coming into contact with the water, losing their strength and their supporting function in order to effect automatic release of the valve-actuating mechanism, the preloading device, loaded by the force of the spring acting against the support-elements, being locked by a locking element extending outwardly from the housing and preventing the spring from being released, the valve-actuating mechanism being brought, as soon as the locking element has been put out of action, to a state of readiness for valve-actuation initiated by the access of water.